Contributed by Inga Gudinaviciene (1), Darius Pranys (1), Pinping Zheng (2), Johan M. Kros (2)
(1) Kaunas Medical University Hospital, Department of Pathology, Kaunas, Lithuania
(2) Erasmus Medical Center Rotterdam, Department of Pathology, Rotterdam,
A 10 months old boy was admitted because of spasticity of both legs and a history of developmental arrest. He had problems with coordination of movements and particularly difficulty in holding position of his head. The head circumference was enlarged.
CT scan revealed occlusive hydrocephalus and a large tumor obstructing the 3rd ventricle. MRI confirmed enlargement of the lateral and 3rd ventricles with periventricular edema (Fig. 1). The tumor measured 3.2 x 2.8 x 3.2 cm. and compressed the thalami and the quadrigeminal plate. The MRI intensity at T1W, T2W, T2W/flair appeared to be close to that of normal gray matter, and there was a less homogenous part in the center of the lesion, showing contrast enhancement (Fig. 1). The large cerebral veins were dislocated by the tumor. A gross total resection was reached by transcortical and transventricular approach.
Histologic examination showed a tumor composed of disorderly arranged mature neuronal and glial cells (Figs. 2A and 2B). The glial cells were invariable immunopositive for GFAP (Fig. 2C). Some cells had bipolar shapes, while most had the morphological characteristics of reactive astrocytes with interconnecting cell processes. The neuronal cells expressed synaptophysin and neurofilament (Fig. 2D). Another tumor component consisted of mature striated muscle cells aligned in bundles and slender fascicles with variable orientation, and in which cross striation was discernible (Fig. 2E). These cells were immunopositive for desmin (Fig. 2F). The third distinct tumor component was represented by clusters of heavily pigmented cells grouped in sheets and small tubules (Figs. 2B and 2G). No rosettes or fleurettes were present. The cells of the sheets and tubules had round to polygonal nuclei. There were scattered small calcifications. Broad strands of collagenous tissue divided the tumor tissue in ill-defined areas and lobules. There were rather inconspicuous tumour vessels. Endothelial proliferation was not seen. There were no primitive elements and no anaplastic or dedifferentiated tumor parts. Immunohistochemistry for MIB-1 (Ki-67 antigen) shows a very low labeling index of all tumor components including the pigmented epithelium, viz., less than 1 % of tumor cells. Positivity was found in the nuclei of some striated muscle cells, some fibroblasts and scattered glial cells.